TY - JOUR
T1 - Effect of NO2 on nocturnal chemistry of isoprene
T2 - Gaseous oxygenated products and secondary organic aerosol formation
AU - Chen, Yi
AU - Tan, Yan
AU - Zheng, Penggang
AU - Wang, Zhe
AU - Zou, Zhouxing
AU - Ho, Kin Fai
AU - Lee, Shuncheng
AU - Wang, Tao
N1 - Funding Information:
This study is supported by the Research Grants Council (RGC) of Hong Kong Special Administrative Region, China ( T24-504/17-N ), National Natural Science Foundation of China ( 91744204 , 42122062 ), French ANR/RGC Joint Research Scheme (project A-PolyU502/16-SEAM ), and Hong Kong Environment and Conservation Fund (project 125/2020 ). The authors would like to acknowledge the HKPolyU University Research Facility in Chemical and Environmental Analysis (UCEA) for the equipment support.
Funding Information:
This study is supported by the Research Grants Council (RGC) of Hong Kong Special Administrative Region, China (T24-504/17-N), National Natural Science Foundation of China (91744204, 42122062), French ANR/RGC Joint Research Scheme (project A-PolyU502/16-SEAM), and Hong Kong Environment and Conservation Fund (project 125/2020). The authors would like to acknowledge the HKPolyU University Research Facility in Chemical and Environmental Analysis (UCEA) for the equipment support.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/10/10
Y1 - 2022/10/10
N2 - As one of the most abundant non-methane hydrocarbon in the atmosphere, isoprene has attracted lots of attention on its oxidation processes and environmental effects. However, less is known about the nocturnal chemistry of isoprene with multiple oxidants coexisting in the atmosphere. Besides, though highly oxygenated molecules (HOMs) have recently been recognized to contribute to secondary organic aerosol (SOA) formation, the specific contribution of measured HOMs on SOA formation in isoprene oxidation has not been well established. In this study, the oxidation of isoprene was simulated under dark and various NO2/O3 conditions. Plenty of oxidation products were identified by combining two state-of-the-art time-of-flight mass spectrometers, and more species with high C and N numbers and low volatilities were detected under high NO2 conditions. The nocturnal oxidation of isoprene was found to be governed by synergic effects of multiple oxidants, including O3, NO3•, and •OH at the same time, and the oxidation proportions changed with NO2. NO2 promoted the formation of most N-containing products especially N2 products, because of the decisive role of NO3• on their formation. Nevertheless, some products such as C5H10O3–5, C5H11NO6, and C10H16N2O10,11 showed a better correlation with HO2NO2 rather than NO2/O3, indicating the importance of HO2• chemistry on the oxidation products formation. Though the concentration of measured oxygenated products was dominated by volatile and semi-volatile organic compounds, the low- and extremely low-volatile organic compounds contributed over 97 % to the SOA formation potential. However, challenges still exist in accurately simulating SOA formation from the measured oxygenated molecules to match the measurement, and further comprehensive characterization of oxidation products in both gas and aerosol phases at the molecular level is needed.
AB - As one of the most abundant non-methane hydrocarbon in the atmosphere, isoprene has attracted lots of attention on its oxidation processes and environmental effects. However, less is known about the nocturnal chemistry of isoprene with multiple oxidants coexisting in the atmosphere. Besides, though highly oxygenated molecules (HOMs) have recently been recognized to contribute to secondary organic aerosol (SOA) formation, the specific contribution of measured HOMs on SOA formation in isoprene oxidation has not been well established. In this study, the oxidation of isoprene was simulated under dark and various NO2/O3 conditions. Plenty of oxidation products were identified by combining two state-of-the-art time-of-flight mass spectrometers, and more species with high C and N numbers and low volatilities were detected under high NO2 conditions. The nocturnal oxidation of isoprene was found to be governed by synergic effects of multiple oxidants, including O3, NO3•, and •OH at the same time, and the oxidation proportions changed with NO2. NO2 promoted the formation of most N-containing products especially N2 products, because of the decisive role of NO3• on their formation. Nevertheless, some products such as C5H10O3–5, C5H11NO6, and C10H16N2O10,11 showed a better correlation with HO2NO2 rather than NO2/O3, indicating the importance of HO2• chemistry on the oxidation products formation. Though the concentration of measured oxygenated products was dominated by volatile and semi-volatile organic compounds, the low- and extremely low-volatile organic compounds contributed over 97 % to the SOA formation potential. However, challenges still exist in accurately simulating SOA formation from the measured oxygenated molecules to match the measurement, and further comprehensive characterization of oxidation products in both gas and aerosol phases at the molecular level is needed.
KW - Isoprene oxidation
KW - Multiple oxidants
KW - Oxygenated organic molecules
KW - Smog chamber
KW - SOA formation
KW - ToF-CIMS
UR - http://www.scopus.com/inward/record.url?scp=85133012394&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2022.156908
DO - 10.1016/j.scitotenv.2022.156908
M3 - Journal article
C2 - 35753484
AN - SCOPUS:85133012394
SN - 0048-9697
VL - 842
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 156908
ER -